Receptor site cavity

Of the diverse supramolecule architectures considered for chemosensor design, we emphasize one—a miniature bucket. Supramolecular buckets maintain a cylindrical cavity with structurally and chemically well-defined upper and lower rims. By virtue of its molecular shape, the bucket is an intrinsic receptor site. A supramolecular bucket alone, however, is an inadequate chemosensor because a signal cannot be produced. In the simplest chemosensing constructs, the analyte generates a signal upon association with the bucket whereas in more elaborate designs, functionality at the rim of the bucket offers sites to attach a discrete reporter site. The thematic focus of this chapter is bucket chemosensors that operate by the 3R scheme shown in Fig. 2, namely, a measurable change in a... 

G. Tovar describes one of the novel chemical applications of modern colloidal systems by using such miniemulsions (in addition to classical suspension polymerization) for molecular imprinting. Here, the stable nanoreactor situation is used to synthesize particle surfaces with molecular sized cavities for biomedically relevant species or species to be separated from each other. Such receptor sites are nowadays preferentially made by the pathways of modern colloid chemistry. 

In cases where the epoxide is chiral, an optically pure form is used to ensure that the resulting ligand is homochiral. These ligqnds assemble into a cone conformation upon complexation with a cavity that varies from being negligible in 93 and 94 (101, 102), to saucer-shaped in 95 (103, 104), to quite deep in 96 and 97 (100, 105). The dimensions and shape of the cavity can be varied according to the ionic radius of the metal ion that is incorporated (103, 104). With Cd(II), the cavity that is created with ligand 96 is an effective receptor site for aromatic anions such as p-toluenesulfonate (100), p-nitrophenolate (100,105-107), (L)-phenylalaninate (106), and p-aminobenzoate (106), all of... 

Endoreceptors and Exoreceptors Host molecules with surface receptor sites are called exoreceptors, while hosts with receptor sites inside cavities are called endoreceptors. Exoreceptors yield a wide array of possibilities when constructing host systems. 

Figure 1. Stereoview of the active site of ADH looking through the protein and out through the entrance cavity of the receptor site. The zinc atom ( ) is tetra-hedrally coordinated to a his and two cys residues. The forth position is occupied by the O atom of the substrate, here, cyclohexanol. The cofactor, NAD-, is shown from front left to center, where the nicotinamide moiety is placed in bonding proximity with the substrate. 

A second application of the index is its use to predict candidate molecules to fill molecular cavities. With the increasing use of molecular graphics, the fit, docking, or intercalation of molecules into cavities in macromolecular simulations becomes an important consideration in drug design. The visualizations of proposed receptor sites, enzyme active sites, and other cavities and spaces of interest in macromolecules make it possible to make measurements of the dimensions of a cavity. Of course, the validity of these images depends on the quality of the input data and the assumptions attending the calculations. If the visualized details of a cavity are to be believed, then there is certainly some interest in what molecules may fit that cavity or some part of it. 

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